Rear-seat airbag and rear-seat airbag apparatus

ABSTRACT

A rear-seat airbag is configured to expand and deploy from a lower portion of a center console of a vehicle toward a center portion of a row of rear seats. The rear-seat airbag includes a first airbag and a second airbag. The first airbag is configured to restrain an upper body of a passenger sitting in the center portion of the row of rear seats. The second airbag is configured to restrain a lower body of the passenger sitting in the center portion of the row of rear seats. The first airbag is coupled to the second airbag such that, when the rear-seat airbag expands and deploys, the first airbag covers a half or more of the second airbag.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent ApplicationNo. 2022-023303 filed on Feb. 17, 2022, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The disclosure relates to a rear-seat airbag and a rear-seat airbagapparatus.

In general practice, in a vehicle such as an automobile, a collisiondetector such as an acceleration sensor is disposed at a vehicle bodyfront and detects a collision from ahead of the vehicle. When thiscollision detector detects a collision from ahead of the vehicle, anairbag apparatus is operated to protect occupants inside a vehiclecabin.

A vehicle with front seats and rear seats is known for including afront-seat airbag apparatus configured to protect occupants sitting inthe front seats such as a driver's seat and a front passenger's seat,and a rear-seat airbag apparatus configured to protect passengerssitting in the rear seats disposed at a rear side of the front seats ina vehicle body.

As a rear-seat airbag apparatus of this kind, a rear-seat airbagconfigured to expand and deploy from a lower portion of a front seattoward a rear side of a backrest of the front seat is disclosed. Therear-seat airbag includes: a front expanding portion configured toexpand and deploy upward along a rear surface of the backrest; a rearexpanding portion configured to expand and deploy rearward from a distalend of the front expanding portion; and a restraint configured torestrain the rear expanding portion to the front expanding portion insuch a manner that the rear expanding portion covers upper portions ofthe thighs of a rear-seat passenger (see, for example, JapaneseUnexamined Patent Application Publication (JP-A) No. 2005-96653).

Research has been also made on an airbag system configured to deployfrom a lap belt that constitutes a seatbelt.

SUMMARY

An aspect of the disclosure provides a rear-seat airbag configured toexpand and deploy from a lower portion of a center console of a vehicletoward a center portion of a row of rear seats includes a first airbagand a second airbag. The first airbag is configured to restrain an upperbody of a passenger sitting in the center portion of the row of rearseats. The second airbag is configured to restrain a lower body of thepassenger sitting in the center portion of the row of rear seats. Thefirst airbag is coupled to the second airbag such that, when therear-seat airbag expands and deploys, the first airbag covers a half ormore of the second airbag.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification. The drawings illustrate an embodiment and,together with the specification, serve to describe the principles of thedisclosure.

FIG. 1 is a top view of a rear-seat airbag according to an embodiment ofthe disclosure, illustrating a deployment form thereof.

FIG. 2 is a perspective view of the rear-seat airbag according to theembodiment of the disclosure, illustrating a configuration thereof.

FIG. 3 relates to the rear-seat airbag according to the embodiment ofthe disclosure and is a diagram illustrating a virtual action pointbased on virtual loci of forward movements of the head, the chest, andthe knees of a passenger upon occurrence of a collision from ahead of avehicle.

FIG. 4 relates to the rear-seat airbag according to the embodiment ofthe disclosure and is a diagram illustrating a relationship of thepassenger, a center console, and the virtual action point immediatelyafter occurrence of the collision from ahead of the vehicle.

FIG. 5 is a diagram illustrating a relationship between a deploymentform of the rear-seat airbag according to the embodiment of thedisclosure and the passenger.

FIG. 6 relates to the rear-seat airbag according to the embodiment ofthe disclosure and is a diagram illustrating the passenger movingforward of the vehicle and the deployment form after occurrence of thecollision from ahead of the vehicle.

FIG. 7 is a block diagram illustrating an electrical configuration ofthe rear-seat airbag apparatus according to the embodiment of thedisclosure.

FIG. 8 is a flowchart of a process flow by a vehicle controller of therear-seat airbag apparatus according to the embodiment of thedisclosure.

DETAILED DESCRIPTION

A rear-seat airbag configured to expand and deploy from a lower portionof a front seat toward a rear side of a backrest of the front seat isdisclosed in JP-A No. 2005-96653. Such a rear-seat airbag isinapplicable to a center portion of a row of rear seats owing to anoriginal circumstance where no front seat exists in front.

In an airbag system configured to deploy from a lap belt, a seatbelt hassuch a property of being in a friction environment constantly thathumidity, for example, may affect the seatbelt and hinder stableoperation of the airbag system. Moreover, upon occurrence of a collisionof a vehicle, the airbag system configured to deploy from the lap beltmay be capable of restraining an upper body of a passenger sitting inthe center portion of the row of rear seats to some extent. However, thecenter portion of the row of rear seats is different from the rear seatson opposite sides in that no such structure as a front seat exists toprevent forward movement of a lower body, mainly the knees, of thepassenger sitting in the center portion of the row of rear seats.Consequently, a behavior of the upper body of the passenger becomes sounstable that damage to the passenger may be increased.

It is desirable to provide a rear-seat airbag and a rear-seat airbagapparatus configured to stably restrain a passenger sitting in a centerportion of a row of rear seats upon occurrence of a collision of avehicle.

Referring to FIG. 1 to FIG. 8 , a rear-seat airbag apparatus 1 accordingto an embodiment of the disclosure will be described. Note that thefollowing description is directed to an illustrative example of thedisclosure and not to be construed as limiting to the disclosure.Factors including, without limitation, numerical values, shapes,materials, components, positions of the components, and how thecomponents are coupled to each other are illustrative only and not to beconstrued as limiting to the disclosure. Further, elements in thefollowing example embodiment which are not recited in a most-genericindependent claim of the disclosure are optional and may be provided onan as-needed basis. The drawings are schematic and are not intended tobe drawn to scale. Throughout the present specification and thedrawings, elements having substantially the same function andconfiguration are denoted with the same numerals to avoid any redundantdescription.

In FIG. 1 to FIG. 6 , arrow FR indicates a front side of a vehicle,arrow BK indicates a rear side of the vehicle, arrow UP indicates anupper side of the vehicle, arrow LH indicates a left side of the vehicle(one side of a vehicle width direction) as viewed from the vehicle upperside, and arrow RH indicates a right side of the vehicle (the other sideof the vehicle width direction).

In the following description, a vertical direction, a fore-and-aftdirection, and a lateral direction are used to respectively indicate avehicle vertical direction, a vehicle fore-and-aft direction, and avehicle lateral direction unless specified otherwise.

EMBODIMENT

Referring to FIG. 1 to FIG. 8 , the rear-seat airbag apparatus 1according to the embodiment will be described.

Configuration of Rear-Seat Airbag Apparatus 1

As illustrated in FIG. 1 , a rear-seat airbag 10 of the rear-seat airbagapparatus 1 according to the embodiment is disposed in a lower portionof a center console 2 of the vehicle, and the rear-seat airbag 10expands and deploys toward a center portion of a row of rear seats.

It is noted that the lower portion of the center console 2 includes afragile portion, which is to be open when the rear-seat airbag 10expands and deploys.

As illustrated in FIG. 2 , the rear-seat airbag 10 in the rear-seatairbag apparatus 1 according to the embodiment includes a first airbag20 and a second airbag 30.

The first airbag 20 expands and deploys to restrain an upper body of apassenger CR sitting in a center portion of the row of rear seats.

The first airbag 20 serves as an upper body restraint bag.

The second airbag 30 expands and deploys to restrain a lower body of thepassenger CR sitting in the center portion of the row of rear seats.When expanded and deployed, the second airbag 30 takes a deployment formwider in the vertical direction.

Opposite ends RP2A and RP2B of the second airbag 30 in the vehicle widthdirection are secured at least to a floor stretching over a centerportion of the vehicle.

Therefore, the second airbag 30 serves as a lower body restraint bag andas a reaction force bag.

The first airbag 20 includes joints RP1A, RP1B, RP1C, and RP1D, whichare four points RP1A, RP1B, RP1C, and RP1D illustrated in FIG. 2 , forexample, where the first airbag 20 is coupled to the second airbag 30such that, when the rear-seat airbag 10 is expanded and deployed, thefirst airbag 20 covers a half or more of the second airbag 30 expandedand deployed.

It is noted that the first airbag 20 is coupled to the second airbag 30at a plane including the four points of joints RP1A, RP1B, RP1C, andRP1D in such a manner that a line dividing the front-side first airbag20 and the rear-side second airbag 30 extends until the passenger CRside in a cross section of the first airbag 20 when expanded anddeployed.

The second airbag 30 includes cylindrical air chambers 30A and 30Bindependent from each other in the vertical direction. When the secondairbag 30 is expanded and deployed, the cylindrical air chambers 30A and30B are coupled to each other so as to sandwich and restrain knees KN ofthe passenger CR.

An inflator, not illustrated, is coupled to the second airbag 30. Aregion of the second airbag 30 that is coupled to the first airbag 20has vent holes, not illustrated, via which high-pressure gas suppliedfrom the inflator is discharged to the first airbag 20.

It is noted that diameters of exhaust openings of the vent holes aredetermined in accordance with a volume of the first airbag 20 and thesecond airbag 30 and a supply amount of the high-pressure gas suppliedfrom the inflator.

In response to an impact generated by a collision of the vehicle, thehead HE, the chest CH, and the knees KN of the passenger CR sitting inthe center portion of the row of rear seats move forward. When therear-seat airbag 10 expands and deploys, a point of intersection ofvirtual loci of these forward movements coincides with a center ofgravity of the rear-seat airbag 10.

In FIG. 3 , arrows (vectors) illustrate the virtual loci of the forwardmovements of the head HE, the chest CH, and the knees KN of thepassenger CR sitting in the center portion of the row of rear seats inresponse to the impact generated by the collision of the vehicle duringexpansion and deployment of the rear-seat airbag 10.

In FIG. 3 , arrow VH indicates the virtual locus of the head HE of thepassenger CR, arrow VC indicates the virtual locus of the chest CH ofthe passenger CR, and arrow VK indicates the virtual locus of the kneesKN of the passenger CR.

That is, as illustrated in FIG. 4 , a disposition location and adeployment form of the rear-seat airbag 10 are determined in such amanner that an intersection point VPA of these virtual loci coincideswith the center of gravity of the rear-seat airbag 10 when expanded anddeployed.

Moreover, the first airbag 20 includes a protrusion CP configured toexpand and deploy above the intersection point VPA of the virtual lociwhen the first airbag 20 expands and deploys.

In one example, as illustrated in FIG. 5 , when the first airbag 20 andthe second airbag 30 expand and deploy, the first airbag 20 expands anddeploys in such a manner that the protrusion CP is formed above theintersection point VPA of the virtual loci.

Furthermore, as illustrated in FIG. 6 , upon occurrence of the collisionfrom ahead of the vehicle, when the passenger CR falls forward of thevehicle, the second airbag 30 expands and deploys in such a manner thatthe intersection point VPA of the virtual loci intersects a centerportion of the two cylindrical air chambers 30A and 30B coupled to eachother in the vertical direction.

Electrical Configuration of Rear-Seat Airbag Apparatus 1

Referring to FIG. 7 , an electrical configuration of the rear-seatairbag apparatus 1 according to the embodiment will be described.

As illustrated in FIG. 7 , the rear-seat airbag apparatus 1 includes avehicle controller 100, a vehicle frontal-collision sensor 110, apassenger detector 120, and an inflator 130.

The vehicle controller 100 includes components such as a centralprocessing unit (CPU), a read only memory (ROM), and a random accessmemory (RAM). The vehicle controller 100 is an electronic control unit(ECU) configured to perform, for example, various kinds of arithmeticprocessing for vehicle control.

It is noted that in the embodiment, the vehicle controller 100 controlsoperation of the inflator 130 based on a sensing signal from the vehiclefrontal-collision sensor 110, described later.

When a collision from ahead of the vehicle occurs, the vehiclefrontal-collision sensor 110 outputs to the vehicle controller 100 asensing signal to the effect that the collision has been detected.

In one example, the vehicle frontal-collision sensor 110 may be anacceleration sensor configured to detect an impact or vibration appliedto the vehicle as an acceleration.

The acceleration sensor may be a piezo-resistive acceleration sensorutilizing a change in electrical resistance of semiconductor or anelectrostatic capacity acceleration sensor configured to detect a gapchange between a movable part and a stationary part of a comb electrodeas an electrostatic capacity.

Alternatively, the acceleration sensor configured to detect a collisionand another acceleration sensor configured to detect an acceleration ofa floor may be provided to determine the collision based on accelerationvalues from both of the acceleration sensors.

The passenger detector 120 detects the passenger CR sitting in thecenter portion of the row of rear seats.

The passenger detector 120 may be a load sensor disposed inside a seatsurface of the row of rear seats or a detection method such as a methodof analyzing a captured image of an inside of a vehicle cabin.

The inflator 130 is disposed in the lower portion of the center console2, and includes the rear-seat airbag 10 folded, an ignition device, anignition agent, a gas generation agent, and a container box configuredto contain these components.

In the inflator 130, when the ignition device is started in response toa control signal from the vehicle controller 100, the ignition agentcatches fire to generate a large amount of gas, which is supplied viathe first airbag 20 and the vent holes that constitute the rear-seatairbag 10 so as to expand and deploy the second airbag 30.

Control of Rear-Seat Airbag Apparatus 1

As illustrated in FIG. 8 , the vehicle controller 100 determines whetherthe passenger CR in the center portion of the row of rear seats has beendetected (step S110). In one example, the vehicle controller 100determines whether the vehicle controller 100 has received, from thepassenger detector 120, a signal to the effect that the passenger CR inthe center portion of the row of rear seats has been detected.

When the vehicle controller 100 detects the passenger CR in the centerportion of the row of rear seats (“YES” at step S110), the vehiclecontroller 100 makes the process proceed to step S120.

Unless the vehicle controller 100 detects the passenger CR in the centerportion of the row of rear seats (“NO” at step S110), the vehiclecontroller 100 resets the process and stands by.

Next, the vehicle controller 100 determines whether a collision hasoccurred at the vehicle front (step S120).

At this time, when the vehicle controller 100 determines that nocollision has occurred at the vehicle front, that is, when the vehiclecontroller 100 determines that the vehicle controller 100 has receivedno sensing signal from the vehicle frontal-collision sensor 110 (“NO” atstep S120), the vehicle controller 100 returns the process to step S110.

When the vehicle controller 100 determines that a collision has occurredat the vehicle front (“YES” at step S120), for example, when the vehiclecontroller 100 determines that the vehicle controller 100 has received,from the vehicle frontal-collision sensor 110, the sensing signal to theeffect that a collision has occurred at the vehicle front, the vehiclecontroller 100 performs control to operate the inflator 130 so as toexpand and deploy the first airbag 20 and the second airbag 30 (stepS130).

Next, the vehicle controller 100 determines whether predetermined timeof gas supply by the inflator 130 has elapsed (step S140).

When the vehicle controller 100 determines that the predetermined timeof gas supply by the inflator 130 has not elapsed (“NO” at step S140),the vehicle controller 100 resets the process and stands by.

At this step, the predetermined time refers to, for example, a period oftime for supplying a sufficient amount of gas to expand and deploy thefirst airbag 20 and the second airbag 30.

When the vehicle controller 100 determines that the predetermined timeof gas supply by the inflator 130 has elapsed (“YES” at step S140), thevehicle controller 100 controls the inflator 130 to stop gas supply bythe inflator 130 (step S150), and ends the process.

Operation and Effect

As described above, the rear-seat airbag 10 of the rear-seat airbagapparatus 1 according to the embodiment expands and deploys from thelower portion of the center console 2 of the vehicle toward the centerportion of the row of rear seats. The rear-seat airbag 10 includes thefirst airbag 20 configured to restrain the upper body of the passengerCR sitting in the center portion of the row of rear seats, and thesecond airbag 30 configured to restrain the lower body of the passengerCR sitting in the center portion of the row of rear seats.

That is, the first airbag 20 restrains the upper body of the passengerCR sitting in the center portion of the row of rear seats so as to serveas the upper body restraint bag. The second airbag 30 restrains thelower body of the passenger CR sitting in the center portion of the rowof rear seats so as to serve as the lower body restraint bag.

Consequently, the rear-seat airbag 10 of the rear-seat airbag apparatus1 serves both as the upper body restraint airbag and as the lower bodyrestraint airbag so that the passenger CR in the row of rear seats canbe stably restrained upon occurrence of the collision of the vehicle.

Moreover, because the rear-seat airbag 10 of the rear-seat airbagapparatus 1 expands and deploys from the lower portion of the centerconsole 2 of the vehicle toward the center portion of the row of rearseats, even the passenger CR in the center portion of the row of rearseats can be stably restrained upon occurrence of the collision of thevehicle though no front seat exists in front of the center portion ofthe row of rear seats.

When the second airbag 30 that constitutes the rear-seat airbag 10 ofthe rear-seat airbag apparatus 1 according to the embodiment is expandedand deployed, the cylindrical air chambers 30A and 30B independent fromeach other in the vertical direction are expanded and deployed whilecoupled to each other, and at least opposite ends of the cylindrical airchambers 30A and 30B in the vehicle width direction are secured to thesecuring points RP2A and RP2B in the floor stretching over the centerportion of the vehicle.

That is, at least the opposite ends of the second airbag 30 in thevehicle width direction are secured to the securing points RP2A and RP2Bin the floor stretching over the center portion of the vehicle.

Consequently, the second airbag 30 serves both as the lower bodyrestraint bag and as the reaction force bag so that the passenger CR inthe row of rear seats can be stably restrained upon occurrence of thecollision of the vehicle.

The first airbag 20 that constitutes the rear-seat airbag 10 of therear-seat airbag apparatus 1 according to the embodiment includes thejoints RP1A, RP1B, RP1C, and RP1D where the first airbag 20 is coupledto the second airbag 30 such that, when the rear-seat airbag 10 isexpanded and deployed, the first airbag 20 covers a half or more of thesecond airbag 30 expanded and deployed.

Therefore, for example, when the first airbag 20 and the second airbag30 are coupled to each other at the joints, which are the four pointsRP1A, RP1B, RP1C, and RP1D, and even when the force generated by thecollision of the vehicle is applied to the passenger CR sitting in thecenter portion of the row of rear seats and makes the upper body of thepassenger CR fall forward of the vehicle, thereby applying pressure tothe first airbag 20, the joints RP1A, RP1B, RP1C, and RP1D enable thesecond airbag 30 to provide reaction force. Thus, upon occurrence of thecollision of the vehicle, the upper body and the lower body of thepassenger CR in the row of rear seats can be stably restrained.

Moreover, when the first airbag 20 and the second airbag 30 are coupledto each other at the plane including the four points of the joints RP1A,RP1B, RP1C, and RP1D, a coupling state of the first airbag 20 and thesecond airbag 30 is strengthened. Consequently, even when the forcegenerated by the collision of the vehicle is applied to the passenger CRsitting in the center portion of the row of rear seats and makes theupper body of the passenger CR fall forward of the vehicle, therebyapplying pressure to the first airbag 20, the coupling at the planeincluding the joints RP1A, RP1B, RP1C, and RP1D enables the secondairbag 30 to provide reaction force. Thus, upon occurrence of thecollision of the vehicle, the upper body and the lower body of thepassenger CR in the row of rear seats can be restrained more stably.

The rear-seat airbag 10 of the rear-seat airbag apparatus 1 according tothe embodiment expands and deploys in such a manner that when the headHE, the chest CH, and the knees KN of the passenger CR sitting in thecenter portion of the row of rear seats move forward in response to animpact generated by the collision of the vehicle, the point ofintersection of the virtual loci of these forward movements coincideswith the center of gravity of the rear-seat airbag 10.

That is, the center of gravity of the rear-seat airbag 10 when expandedand deployed coincides with the point of intersection of the virtualloci of the forward movements of the head HE, the chest CH, and theknees KN of the passenger CR sitting in the center portion of the row ofrear seats in response to the impact generated by the collision of thevehicle.

Consequently, with respect to such moving forward behaviors by the headHE, the chest CH, and the knees KN of the passenger CR sitting in thecenter portion of the row of rear seats owing to the impact generated bythe collision of the vehicle, the first airbag 20 and the second airbag30 are deployed while uniformly disposed.

Therefore, upon occurrence of the collision of the vehicle, thepassenger CR sitting in the center portion of the row of rear seats canbe stably restrained.

When expanded and deployed, the first airbag 20 that constitutes therear-seat airbag 10 of the rear-seat airbag apparatus 1 according to theembodiment has the protrusion CP expanded and deployed above the pointof intersection of the virtual loci.

That is, the first airbag 20 expands and deploys in such a manner thatthe protrusion CP filled with sufficient high-pressure gas is formedabove the point of intersection of the virtual loci.

Consequently, as the head HE, the chest CH, and the knees KN of thepassenger CR sitting in the center portion of the row of rear seats moveforward due to the impact generated by the collision of the vehicle, theprotrusion CP filled with sufficient high-pressure gas first enfolds andrestrains the head HE of the passenger CR, and then, part of theprotrusion CP that has been deformed by the restraint enfolds andrestrains the chest CH of the passenger CR.

Therefore, upon occurrence of the collision of the vehicle, the upperbody of the passenger CR sitting in the center portion of the row ofrear seats can be stably restrained.

Moreover, upon occurrence of the collision from ahead of the vehicle,when the passenger CR falls forward of the vehicle, the second airbag 30that constitutes the rear-seat airbag 10 of the rear-seat airbagapparatus 1 according to the embodiment expands and deploys in such amanner that the intersection point of the virtual loci intersects thecenter portion of the cylindrical air chambers 30A and 30B coupled toeach other in the vertical direction.

That is, the second airbag 30 expands and deploys to make theintersection point of the virtual loci intersect the center portion ofthe cylindrical air chambers 30A and 30B coupled to each other in thevertical direction so that the second airbag 30 is disposed uniformlywith respect to the knees KN of the passenger CR sitting in the centerportion of the row of rear seats.

Therefore, upon occurrence of the collision of the vehicle, the lowerbody of the passenger CR sitting in the center portion of the row ofrear seats can be stably restrained.

Furthermore, when the second airbag 30 expands and deploys to make theintersection point of the virtual loci intersect the center portion ofthe cylindrical air chambers 30A and 30B coupled to each other in thevertical direction, a joint of the cylindrical air chambers 30A and 30Bcontacts the front of the knees KN of the passenger CR, an expansion ofthe upper cylindrical air chamber 30A contacts leg parts of thepassenger CR above the knees KN, and an expansion of the lowercylindrical air chamber 30B contacts leg parts of the passenger CR belowthe knees KN. Thus, upon occurrence of the collision of the vehicle, theknees KN of the passenger CR sitting in the center portion of the row ofrear seats can be restrained stably from three directions.

When the vehicle controller 100 of the rear-seat airbag apparatus 1according to the embodiment receives, from the passenger detector 120,the signal to the effect that the passenger detector 120 has detectedthe passenger CR in the center portion of the row of rear seats, andwhen the vehicle controller 100 determines that the collision hasoccurred at the vehicle front, the vehicle controller 100 performscontrol to operate the inflator 130 so as to expand and deploy the firstairbag 20 and the second airbag 30.

That is, generally, the passenger CR sits in the rear seat of thevehicle less frequently than the passenger CR sits in the frontpassenger's seat of the vehicle, and the passenger CR sits in the centerportion of the row of rear seats even less frequently.

For this reason, when the signal to the effect that the passenger CR inthe center portion of the row of the rear seats has been detected isreceived from the passenger detector 120, and when it is determined thatthe collision has occurred at the vehicle front, control is performed tooperate the inflator 130 so as to expand and deploy the first airbag 20and the second airbag 30.

First Modified Example

In the description of the embodiment, the second airbag 30 includes thetwo cylindrical air chambers 30A and 30B coupled to each other.

However, this is not to be construed in a limiting sense. For example,the second airbag 30 may include three cylindrical air chambers coupledto one another.

In this case, an upper cylindrical air chamber in the vertical directioncontacts the leg parts of the passenger CR above the knees KN, a lowercylindrical air chamber contacts the leg parts of the passenger CR belowthe knees KN, and an intermediate cylindrical air chamber contacts thefront of the knees KN of the passenger CR. Thus, upon occurrence of thecollision of the vehicle, the knees KN of the passenger CR sitting inthe center portion of the row of rear seats can be restrained stablyfrom three directions.

Second Modified Example

In the description of the embodiment, when the passenger detector 120fails to detect the passenger CR sitting in the center portion of therow of rear seats, the rear-seat airbag 10 is not expanded and deployed.

However, when airbags are provided for the rear seats on opposite sides,the rear-seat airbag 10 may be expanded and deployed even when thepassenger detector 120 fails to detect the passenger CR sitting in thecenter portion of the row of rear seats.

That is, without having detected the passenger CR sitting in the centerportion of the row of rear seats, the rear-seat airbag 10 is expandedand deployed. Thus, upon occurrence of a collision from diagonally aheadof the vehicle, for example, when passengers CR sitting in the rearseats on opposite sides exhibit yawing behaviors, the first airbag 20expanded and deployed is present in loci of the yawing behaviors so asto restrain upper bodies of the passengers CR.

It is noted that the rear-seat airbag apparatus 1 according to theembodiment of the disclosure can be implemented by recording the processby the vehicle controller 100 on the recording medium readable by thecomputer system, and by causing the vehicle controller 100 to read theprogram recorded on the recording medium and execute the program. Thecomputer system in this description includes an OS and hardware such asperipheral devices.

The “computer system” also includes a homepage providing environment (ordisplay environment) when the World Wide Web (WWW) system is used. Theprogram may be transmitted from the computer system with the programstored in a storage, for example, to another computer system via atransmission medium or by a transmission wave in the transmissionmedium. In this description, the “transmission medium” configured totransmit the program refers to a medium serving to transmit information,for example, a network (communication network) such as the Internet or acommunication line such as a telephone line.

The program may serve to implement some of the above-describedfunctions. Furthermore, the program may be what is called a differencefile (difference program), with which the program already recorded onthe computer system can be combined to implement the functions.

Although the embodiment of the disclosure has been described in detailheretofore with reference to the drawings, configuration examples arenot to be limited to the embodiment but may include designs, forexample, within the scope of the subject matter of the disclosure.

1. A rear-seat airbag configured to expand and deploy from a lowerportion of a center console of a vehicle toward a center portion of arow of rear seats, the rear-seat airbag comprising: a first airbagconfigured to restrain an upper body of a passenger sitting in thecenter portion of the row of rear seats; and a second airbag configuredto restrain a lower body of the passenger sitting in the center portionof the row of rear seats, wherein the first airbag is coupled to thesecond airbag such that, when the rear-seat airbag expands and deploys,the first airbag covers a half or more of the second airbag.
 2. Therear-seat airbag according to claim 1, wherein a center of gravity ofeach of the first airbag and the second airbag when the first airbag andthe second airbag expand and deploy is configured to coincide with apoint of intersection of virtual loci of forward movements of a head, achest, and knees of the passenger sitting in the center portion of therow of rear seats in response to an impact generated by a collision ofthe vehicle.
 3. The rear-seat airbag according to claim 2, wherein thefirst airbag comprises a protrusion configured to expand and deployabove the point of the intersection of the virtual loci when the firstairbag expands and deploys.
 4. The rear-seat airbag according to claim3, wherein the second airbag comprises cylindrical air chambers coupledto each other in a vertical direction, and the second airbag isconfigured to, when the passenger falls forward of the vehicle uponoccurrence of a collision from ahead of the vehicle, expand and deploysuch that the point of the intersection of the virtual loci intersects acenter portion of the cylindrical air chambers.
 5. The rear-seat airbagaccording to claim 1, wherein the cylindrical air chambers which areindependent from each other in the vertical direction are configured to,when the second airbag expands and deploys, expand and deploy whilecoupled to each other, and both ends of each of the cylindrical airchambers in a vehicle width direction are secured to a floor stretchingover a center portion of the vehicle.
 6. The rear-seat airbag accordingto claim 2, wherein the cylindrical air chambers which are independentfrom each other in the vertical direction are configured to, when thesecond airbag expands and deploys, expand and deploy while coupled toeach other, and both ends of each of the cylindrical air chambers in avehicle width direction are secured to a floor stretching over a centerportion of the vehicle.
 7. The rear-seat airbag according to claim 3,wherein the cylindrical air chambers which are independent from eachother in the vertical direction are configured to, when the secondairbag expands and deploys, expand and deploy while coupled to eachother, and both ends of each of the cylindrical air chambers in avehicle width direction are secured to a floor stretching over a centerportion of the vehicle.
 8. The rear-seat airbag according to claim 4,wherein the cylindrical air chambers which are independent from eachother in the vertical direction are configured to, when the secondairbag expands and deploys, expand and deploy while coupled to eachother, and both ends of each of the cylindrical air chambers in avehicle width direction are secured to a floor stretching over a centerportion of the vehicle.